BIODIVERSITY: Endemic Plants
Barleria lebomboensis I.Darbysh., McCleland & Froneman
Photographs of Barleria lebomboensis in the field. A. Flower, face view. B. Inflorescence with open flower. C. Flower, lateral view. D. Inflorescence. E. Mature leaves. F. Habit and habitat. All taken by W. McCleland, Mhlumeni, Swaziland, 6 June 2016
This species was collected by James Culverwell in 1977, identified as B. meyeriana, but a new population of this species was found in 2016, and this led to the formal description of Barleria lebomboensis.
Information extracted from Barleria lebomboensis (Acanthaceae), an endangered new species from the Lebombo Mountains of Swaziland, Phytotaxa, 2017:
Description: Perennial herb with numerous trailing or procumbent stems from a woody base and rootstock, stems to 200-250 mm long, distal portion sometimes decumbent. Stems red-brown, later turning greenish, subangular, with numerous pale ascending to sub-spreading bristly hairs 0.7-1.1 mm long throughout, these sometimes with a bulbous base, and with short finer spreading hairs mostly on two opposite sides, distal-most internodes also with patent glandular hairs. Leaves sessile; or with petiole 3 mm long, broad and winged, with bristly hairs beneath; blade bluish-green often with purplish margin and veins beneath or suffused purple throughout abaxially, broadly ovate, 17-30 x 11.5- 23.0 mm (length:width ratio 1.15-1.75(-2):1), base shallowly cordate or truncate, apex acute or obtuse, minutely apiculate, adaxial surface glabrous, margin and main veins beneath with pale ascending hairs, often with a bulbous base, sometimes also with few short patent glandular hairs along margin of proximal half; lateral veins 3-5 pairs, ascending; cystoliths conspicuous on adaxial surface in dried material. Inflorescence a contracted terminal spike 20- 30 mm long, comprising a series of single-flowered opposite cymes; bracts foliaceous, but reducing upwards and becoming more elliptic or obovate, typically 11.5-15.5 x 4-7 mm, bracts of distal flowers can be oblanceolate and only 2.5 mm wide, indumentum as that of leaves, but glandular hairs often more numerous and can also be on the abaxial surface; bracteoles spathulate or linear-spathulate, 9.0-13.2 x 0.8-2.0 mm, apex acute or obtuse, often purple tinged towards apex and/or along margin, midrib prominent, strigulose, surface glandular-pubescent at least along margin. Calyx green in proximal portion, purple distally and along margin; anterior lobe oblong-lanceolate, 11-13 x 2.7-3.3 mm, widest at base, apex acute or usually notched for up to 1 mm, external surface with 4 or 6 prominent parallel veins, patent glandular pubescent and veins also ascending-strigose; posterior lobe as anterior lobe, but 11.7-13.7 mm long, marginally narrower, apex acute, surface with (3 or) 5 prominent veins; lateral lobes linear-lanceolate, 6.5-10.0 x 1.0-1.3 mm, glandular-pubescent in distal half. Corolla pale blue or lilac with a white tube, lobes with marginally darker midvein, 21.0-25.5 mm long, shortly glandular- and eglandular-pubescent externally especially on lateral lobes; tube 10.0-12.5 mm long, widening slightly above insertion point of stamens, mouth 3.8-4.5 mm wide; limb 5-lobed, abaxial lobe only very slightly offset from other lobes by 1.0-1.7 mm, broadly obovate, 10.5-11.0 x 8.0-8.5 mm, apex emarginate, lateral lobes elliptic, 10.0-11.5 x 5.7-7.0 mm, apex rounded or emarginate, adaxial lobes as lateral lobes but narrower, 9.8-10.5 x 4.3-5.0 mm. Stamens inserted +/- 5.5 mm from base of corolla tube, filaments +/- 15.5 mm long, flattened and glandular-puberulent towards base; anthers exserted, 2.8-3.2 mm long; lateral staminodes 1.2-1.5 mm long, glandular-puberulent, adaxial staminode somewhat shorter. Ovary puberulent; style glabrous; stigma purple, linear, curved 1.6-1.8 mm long, with shallowly 2-lobed apex. Capsule 2-seeded, +/- 11 mm long including prominent beak 4.5 mm long, eglandular-puberulent, hairs spreading or slightly antrorse; seeds only seen in immature state, 4 x 3 mm, with wavy cream-coloured hygroscopic hairs.
Differs from Barleria meyeriana in the leaves being broadly ovate, length:width ratio 1.15-1.75(-2) (versus in B. meyeriana leaves lanceolate or more rarely ovate, length:width ratio (1.5-)2-4(-6)), with base shallowly cordate or truncate (versus cuneate to rounded) and the lower surface conspicuously pubescent on the main veins and margin (versus lower surface with hairs restricted to margin and midrib); the inflorescence being a contracted spike (versus a lax spike with at least the lower flowers widely spaced); the corolla being markedly smaller, 21.0-25.5 mm (versus 35-48 mm) long; the limb and throat without darker markings (versus corolla with a conspicuous darker line running from the centre of the proximal portion of each lobe into the throat); and the capsule puberulent throughout (versus glabrous or puberulent only on the beak) and shorter, c. 11 mm (versus 14-17 mm long).
Differs from Barleria dolomiticola in the corolla limb being subregular, the abaxial lobe barely offset from the other four lobes (versus in B. dolomiticola corolla in marked 4+1 configuration, the abaxial lobe offset by 6-7 mm from the other four lobes); the corolla being smaller, 21.0-25.5 mm long (versus 30-50 mm), with the limb and throat without darker markings (versus corolla with conspicuous darker lines running from both the centre of the proximal portion of each lobe and the sinuses between the lobes into the throat); and the long eglandular stem and leaf hairs being ascending or sub-spreading and simple (versus hairs stiffly appressed and biramous).
Distribution: Swaziland, Lebombo Mountains, between the Mbuluzi River and Siteki.
Conservation Status: Barleria lebomboensis is here assessed as Endangered EN B1ab(iii)+2ab(iii), following the Categories and Criteria of IUCN (2012). Justification for this assessment is the very small extent of occurrence of this species (estimated as a maximum of approximately 80 km2 based upon modelling of its ecology), very small area of occupancy (estimated at less than 1 km2), its occurrence at two locations and an inferred decline in habitat status through overgrazing and an increase in cultivation of summit grasslands within its range. The type locality is in the proposed Mhlumeni Community Conservation Area, an ecotourism initiative within the Lubombo Conservancy. However, this site does not have any formal conservation status at present and it is still heavily grazed. This species may also qualify as Endangered under Criterion C, but more complete population data are needed before this can be confirmed.